Volume 60, Issue 5

A Hallstatt period burial mound (tumulus) in Schandorf, Burgenland, Austria, was opened and archaeologically investigated in 2021. Not only numerous pottery fragments, but also some garment buttons were found, one of which was provided for metallographic examinations, aiming at identifying the method of manufacture: soldering, riveting, casting? Prior to the metallographic examinations, micro-computed tomography (μm CT) was carried out at a resolution of 5 μm. The Figures show that large areas are oxidized. It was, however, found that metallic portions still existed. The overall appearance suggests investment casting as the manufacturing method. Analytical measurements revealed that the material is tin bronze. Despite severe corrosion, the metallographic sections still exhibit a clearly recognizable cast structure. There are presumably two types of corrosion: first, high temperature corrosion, which resulted in the formation of bronze oxides in the grain boundary areas during the cremation, and, second, corrosion in an aqueous environment, during which malachite formed. So far, no comparable studies can be found in the literature.

Distinct AZ80A-Mg alloy with AA6061-Al alloy plates were joined using friction stir welding and investigation regarding the weld features of the fabricated joints, related to microstructural attributes and mechanical properties was carried out by employing distinctive tool rotational speeds (1600, 1400, 1200, 1000 and 800 rpm). Tool possessing cylindrical pin with tapered profile was employed at constant traverse speed of 30 mm/min and was inserted towards AA6061 alloy plate at 0.5 mm offset distance. Experimental observations revealed that employment of tool rotational speed of 1200 rpm have generated ideal amounts of frictional heat, which have softened the ingredients of both the parent metals and have contributed for the transition of the grains into dynamically recrystallized, finely refined structures being distributed evenly in nugget zone. Moreover, this joint exhibited a tensile strength of 224 MPa (nearly 77.78 % of the tensile strength of AZ80A and 72.26 % of AA6061 alloy). Presence of river like patterns, rifts, tear crinkles at the middle portions of fractured surfaces, announced the brittle category of fracture of the flaw free joint and exhibited fracture at the horizon of the thermomechanically influenced zone and the nugget zone on retreatment side, where the warped structures have fused together.

Transverse through-wall airfoil cracking was found in a row 3 twin turbine vane segment of a type used in heavy-duty gas turbine engines for power generation. A laboratory investigation determined liquation cracking (LC), a hot cracking mechanism, as the metallurgical cause of failure. As became apparent only after the investigation, the root cause of failure was a malfunctioning plasma gun used for thermal spraying the thermal barrier ceramic top coat onto the subject part.

This article tries to work out how scientific data are generated and what causes lead to incorrect data. For this purpose, interactions between humans, computers and machines are analyzed. The handling of incorrect data that has already been published must also be clarified. The final, ethical question is: to what extent are people responsible for their actions if their decisions are shaped by incorrect data that are scientifically proven?